the Bosch is A better choice in my opinion.

Well you didn't just start throwing parts at it.
Which can get costly, and is a poor way to procced.

With a little coaching you went through a diagnostic process that points at the MAF sensor.
When you get the sensor and install it, that will prove how good or bad the diagnostic method was.
Then you can keep (if good) or discard (if bad) and build on your diagnostic methodology.

There is a way to test a MAF sensor with a volt meter but I don't know the values or the procedure.

As for hoping it works- does keeping one fingers crossed help:confused:

Ya, I feel like it is still somewhat of a gamble - but one that the odds are in my favor. I think the troubleshooting methodology is similar to what a good shop would do, difference being, I can’t swap in a new MAF, verify results, and if found that was not the correct diagnosis, save the “new” MAF sensor for the next customer.

A good shop would have a Pico scope or something similar and a Tech. who was well versed in reading the wave forms.
They could test the MAF (and any other sensor) without removing it from the car and know what condition it was in.

If you have the time or inclination look up ScannerDanner on U-tube he is very good with them.
Aside from the Pico or Snapon scanners he uses his diagnostic methodology is top notch.
Lots can be learned from him and his methods.

Anyway my feelings are going to be hurt if we are wrong about the MAF. LOL

I looked up scannerdanner and I have seen some of his videos on other subjects besides fuel trims and maf sensors. Good stuff.

I just watched a very interesting video in which he had a car that had similar symptoms to mine and it was a brake booster leak.

Then he showed the disconnect the maf test doesn’t work because he disconnected the MAF and it “fixed” the problem. That car was using MAP instead when maf disconnected (which isnt affected by vacuum leak). Boxsters don’t have MAP sensor correct? What is the computer’s strategy for when the MAF is disconnected?

I reread my posts and realized the way I measured the engine vacuum when I tested it was by removing the brake booster vacuum line. So if the booster is the problem, then I just happened to eliminate it from the system when I tested it!

Going to check into the brake booster before installing new MAF. Part should be here on Saturday.

Correct the Boxster does not have MAP. (manifold absolute pressure I think??) This is why I suggested you unplug the MAF.
When you disconnect the MAF sensor on the Boxster it forces the Computer to go to a default fuel program which allows it to run relatively well under general conditions.
Not all cars trucks ECU's are programed that way. A friends Ford truck will not even start with the MAF disconnected.

Yes you could redo your vacuum test to include the brake booster for peace of mind.. There should be a hose coming off the intake that you can tee into. Or use a tee fitting at the brake booster;)

The MAF came today. I stuck it in and drove it around with the scanner.

Everything seems good! I don’t want to declare yet that it is fixed but I think it is. Power is good. Fuel trims are good.

I didn’t bother to check the brake booster because it was raining and I don’t think I have any braking problems. I was going to pull the vacuum line out of the boostrer and stick my finger over the end of it while watching the fuel trim. If it is the booster then the short term trim should immediately start to slew downward with the end of the hose plugged and leak stopped.

Sounds like a positive result to me.
Clear the codes out an continue to monitor.
Check for pending codes now and then.

Vtx

I for got to mention in earlier posts that elevation has an affect on vacuum test gauge readings.
The gauges are calibrated for sea level.
So for ever 1000 ft. above sea level the gauge will show 1 in/gh less then it would at sea level.
So add back in 1 in/gh for ever 1000 feet you are above sea level to your gauge reading.
Hope that makes sense.

Makes sense - I’m at 800’.

Now I have a P0430 code with no other codes and everything running smooth. Going warm up the cats and take a look at secondary O2 sensor readings tomorrow.